Various cutting tools in CNC milling are used to plunge, slot or make 3D contouring. The ball nose end mill is also one of those cutting tools. Its unique manufacturing and utilization in the CNC machining process makes it widely popular among machinists.
Like any other cutting tool available in the market, the ball nose end mill is also available in the market in a wide range of flutes. The ball nose end mill with 2 flutes and 4 flutes are most commonly used.
In this article we will discuss what are the ball nose end mills, what are its functions, how it is manufactured and what are the main differences between 2 flute ball nose end mill and 4 flute ball nose end mills.
WHAT IS A BALL NOSE END MILL?
Also known as the ball mills or full radius end mills, the ball nose end mill is cutting tools in which the radius of the nose is half of the tool’s diameter. With this function, the ball nose end mill delivers a curved smooth surface on a workpiece with a constant single radius at the end of the tool without any straight edge.
The ball nose end mills are used as roughing tools but their primary usage is for dies and molds where 3D contouring, corner picking, slotting or profiling with a semi-finished or finished surface is required.
The manufacturing process of ball nose end mills are same as carbide end mills except that the grinding wheel, installed on CNC machine, consists of diamond embedding. Because of the sophistication of the tool, multiple grinding wheels are used that has varying grits, diameter and profile shapes depending upon the tool’s design.
The main challenge is the construction of shape of ball at the tool’s tip which is manufactured using relief that creates ball’s radius at the end of the ball mill. Various other parameters are set on the machine to deliver the required ball mill.
Since the ball nose end mill has a ball at its tip, it is widely used to create big corner radiuses, full grooving, contour milling, shallow slotting, pocketing etc. The ball nose end mills with smaller diameters are used for engraving on the workpiece. Due to its ability to create great round edges, it is also used to create excellent 3D contouring.
To determine how the ball nose end mills works, following are some brief explanation on its parameters:
Cutting reach and depth
The cutting depth on a workpiece is dependent on the contact length of ball nose end mill. The length of the tool ensures precise cutting on a workpiece and prevents from overhanging. To calculate the tool’s length, multiply the cutter dia by 5.
The ball nose end mill’s cutter diameter is responsible to deliver required width of the slot. The cutter diameter also affects the chip removal rate during side milling. Therefore, before purchasing, it is necessary to ensure what is the tool’s cutter diameter and will it deliver the requirements.
DIFFERENCE BETWEEN 2 FLUTE BALL NOSE AND 4 FLUTE BALL NOSE END MILL
Before knowing the difference between the two flutes in a ball mill, it is necessary to understand what is the basic function of flutes in any end mill. The flutes are spiral grooves, with sharp edges in an end mill’s surface. Its basic function is forming chips of material and its evacuation during milling. The harder material will require more flutes and softer material will require less flutes.
The function of 2 flutes in the ball nose end mill is creating slots and grooves on softer materials like wood or aluminum. Because the 2 flute ball nose end mill can also be applied vertically on the workpiece, it can also plunge. However, the ball nose end mill with 2 flutes is unable to work similar to 4 flute end mills.
On the contrary, the 4 flute ball nose end mill is mostly used for side milling and surface milling. Increasing the number of flutes in an end mill will deliver smoother finished surface but simultaneously increase chip load and lesser chip evacuation. But ball nose end mill with 4 flutes is widely used because it works on most of the material and also performs somewhat similar function to 2 flute end mill. So there is no necessity for specifically purchasing ball nose end mill with 2 flutes if 4 flute ball nose end mill can be afforded.
FACTORS THAT DEPEND ON FLUTES IN BALL MILL
Following factors affect the workmanship with ball nose end mill having any number of flute. Therefore, it is necessary to consider the factors while making a selection.
Chips clearing ability
The number of flutes in ball nose end mill affects heavily on the tools ability to clear chips. The more flute ball nose end mill have, the shorter the flute length which may clog the flute and break the tool.
The ball nose end mill with more flutes will deliver smooth surface compared to 2 flute end mill therefore it is used mostly on soft materials like aluminum, wood etc.
The ball nose end mill with 4 flutes will increase productivity because of increased feed rate. This is because 4 flutes are efficient to create longer chips and evacuates them easily in softer materials.
WHY USERS PREFER 4 FLUTE BALL NOSE END MILL OVER 2 FLUTE BALL NOSE END MILL
The modern times, specialized cutting tools are preferred that are not only economical but also have ability to perform multiple functions. This will reduce the cost to buy individual tools for different purposes.
The 2 flute end mills are great cutting tools that delivers lower chip load and works on harder material. Comparatively, the 4 flute end mills are attracting popularity due to its versatility and ability to perform many functions compared to 2 flute end mills.
In earlier times, India, Turkey, Euro, Egypt and USA etc. utilized 2 flute ball nose end mills but with the growing demand and increased production cost, they have moved to more flexible and versatile 4 flute ball nose end mill. The survey reported the strategy has saved much production costs of CNC machinists.
In this article, we will cover the basic function between 2 flutes and 4 flutes end mills, what is the function of ball nose end mill in CNC milling, and finally, why users are now preferring 4 flute ball nose end mill over 2 flute ball nose end mill.
WHY USERS PREFER 4 FLUTE BALL NOSE END MILL OVER 2 FLUTE END MILL
Different materials produce different types of chips; the harder material is brittle in nature which is why it creates smaller brittle chips. Therefore, it requires cutting tools having fewer number of flutes to quickly escape the chips. This is why 2 flute end mills were commonly used.
On the contrary, the soft material produces long chips and so it requires cutting tool having more flutes. For softer materials, 4 flute end mills are used.
But recently, users found with their experience that 4 flute end mills are more beneficial for them as compared to the 2 flute end mills. This is because not only 4 flute end mills cover wide range of harder materials, but also works on soft materials and delivers smoother finish on hard and soft materials where 2 flute end mills fail. This is the main reason CNC machinists around the globe are now utilizing 4 flute end mills on materials with acceptable hardness range. This in turn has saved much production cost.
The ball nose end mill is used to deliver 3D contouring, milling, profiling and slotting with much smoother and finished surface. The ball at the cutting end of the end mill quickly cuts the material smoothly giving finished surface. The ball nose end mills with 4 flutes are now utilized extensively because they can work on a very wide-range of materials from soft to hard nature and give great finished product.
TECHNICAL BENEFIT OF 4 FLUTE BALL NOSE END MILL OVER 2 FLUTE BALL NOSE END MILL
Following are the technical specification of 4 flute end mills that make them superior and recommended over 2 flute ball nose end mill:
Chip evacuation – The 4 flute ball nose end mills is better than 2 flute ball nose end mill because it evacuates harder as well as soft material chips. The hard material breaks into smaller brittle chips like metal, bronze etc. while softer materials like wood or aluminum etc. chips into longer flexible material. The ball nose with 4 flutes evacuates them all quickly.
Wear time – The longer the tool, the more prone it is to wearing. But comparative to more number of flutes, the 4 flute ball nose end mill shows wear time because its ball shape provides smooth rounded contact with the workpiece and also offers less resistance to material on longer operation.
Vertical accuracy – The 4 flute ball nose end mill are longer than 2 flutes so they can plunge more deeply into the material and offer precise accuracy comparatively. The 2 flute ball nose end mill have lesser cutting depth due to less flute which is why it is unable to plunge deeper and accurately.
Surface roughness – Surface roughness is the irregularities on a workpiece. The 4 flutes ball nose end mill mills the material with higher surface roughness because firstly it has round shapes providing smooth surface contact and increased flute allow uneven surfaced material to evacuate easily.
Performance on soft and hard material – This is the biggest advantage of all. The 4 flute ball nose end mill works on many hard materials and works on soft material. The 2 flute end mill is unable to evacuate longer chips produced by soft materials which is 4 flute ball nose end mill exceeds the 2 flute ball mill.
Surface finish – The ball nose end mill with 4 flute provides smoother finish because it has more flutes compared to 2 flutes. It is therefore used on materials where more smoothness is required on slotting, plunging etc.
The ball nose end mills are great cutting tools that delivers smooth rounded surfaced compared to other end mills. Due to its functionality, it is preferred in making 3D contouring and rounded edges. The ball nose with 2 flutes are used on hard materials like metal while 4 flutes ball nose end mill deliver smoother finish and used to mill, plunge or slot softer materials.
The 4 flute ball nose end mill works on various hard materials and also works on soft materials where 2 flute end mills fails. This is what gives an edge to 4 flute end mills. The good surface finish, faster chip evacuation and longer wear time of 4 flute end mill are why they are more widely used across the globe by many product manufacturers.